Test of a prototype of lightweight, active mirrors

Abstract

Lightweight mirrors have been used widely in ground-based imaging systems and astronomical telescopes, because of their light weight and good stiffness. However, space telescope mirrors cannot maintain their initial surface shape due to the effects such as gravity release, thermal changes in the space and so on. To deal with the problem, a new type of lightweight, active primary mirrors which are rib-stiffened and contain surface-parallel actuators embedded in the recess of the ribs, are designed for potentially using in space-based imaging systems. They enable larger primary aperture to improve resolution and sensitivity and are capable of on-orbit surface shape correction, which can control the shape of the mirrors to optical tolerances. According to the previous optimized parameters a prototype of lightweight, active mirrors is fabricated and tested. The influence functions of the fabricated prototype are measured by using a Veeco interferometer and the correctability for the Zernike aberrations is simulated. The results show that it has a good fitting ability for low order Zernike aberrations.